Reporters and pundits don't always get it right. Take the Supreme Court's decision on Arizona's immigration law.

Many media outlets said the Court struck down most of the law. In reality, nearly all of the law had already been upheld in a federal district court ruling. Only four provisions remained at issue before the Supreme Court.

The high court wound up throwing out three of those provisions, giving the administration a mathematical victory perhaps. But the Court firmly upheld the fourth provision, which Arizona Gov. Jan Brewer correctly called the "heart" of the law. That provision allows Arizona law enforcement personnel, once they've arrested someone, to check the suspect's immigration status if they have a "reasonable suspicion" that he or she is in the country illegally.

But checking the immigration status of arrestees is not all Arizona -- or any other state -- can do to combat the problems created by illegal immigration. Those other initiatives that passed muster in district court remain valid, too.

One provision bars state or local officials from implementing policy that impedes enforcement of federal immigration laws. So, unlike California and New York, there will be no "sanctuary cities" in Arizona.

Another provision assures that state and local officials will cooperate fully with agencies trying to determine an applicant's eligibility for welfare and other public benefits, providing all available information about the applicant's immigration status. They must also provide the information to verify residency claims or eligibility for licenses.

Cracking down on illegal day-labor spots, the law makes it a misdemeanor for drivers to block or impede traffic while trying to hire or pick up passengers for transportation to a worksite.

Another provision makes it a felony to "intentionally engage in the smuggling of human beings for profit or commercial purpose." The law defines smuggling quite broadly to include transporting anyone who a driver "knows or has reason to know" is not in the country legally. The state may also impound vehicles used for this purpose.

The state statute even manages to put a little pressure on the feds to enforce their own federal law. Now, once an illegal immigrant completes a prison sentence for violating a state law, Arizona officials will notify immigration authorities of his pending release. How politically embarrassing if the feds should then refuse to pick up convicted criminals known to be here illegally.

All of these measures reflect plain common sense -- and all could be enacted elsewhere. But perhaps the greatest finding of the Supreme Court ruling is its reaffirmation of the constitutional principle of federalism.

As the majority opinion noted, this "central" principle holds that "both the National and State Governments have elements of sovereignty the other is bound to respect." In other words, the states can exercise some control over immigration within their borders.

They need not be passive patsies if the Feds drop all pretense of providing border security. Rather than let millions of illegal immigrants strain their welfare, health and education systems to the breaking point, states can act to mitigate the problem.

That's what Arizona did. Faced with a massive influx of illegal aliens (now comprising as much as 6 percent of the state's population) that produced, according to the Court ruling, an "epidemic of crime, safety risks, serious property damage, and environmental problems," Arizona asserted its sovereign rights and enacted a law to address these problems within its borders. The courts have blessed all but three of that law's provisions.

One of the beauties of federalism is that it allows for a competition of ideas among the states. That's what is shaping up now in the West. Saddled with the same immigration-related problems as Arizona, California is on its way to taking a far different response.

Lawmakers in Sacramento just passed a bill to block local law enforcement from referring anyone for federal deportation unless they've been convicted of a violent or "serious" felony. Backed by more than 100 "immigrant rights" groups, the bill's supporters have dubbed it the "anti-Arizona" proposal.

It will be interesting to see how this policy competition between two "laboratories of democracy" pans out. But given the extraordinary costs of illegal immigration, the smart money will be riding on Arizona.